The configuration of lipid in membranes as a single bilayer has been shown to be a unique state that can self-assemble only at a critical temperature, the physiological temperature of the cell, and with a critical composition that reflects metabolic processes within the membrane and cytosol of the cell. The principles which govern the conditions for assembly of the critical unilamellar state of the membrane has been the primary focus of this project. We have applied these principles to Alzheimer's disease brain tissue, and have observed a lipid defect in membranes that is tissue specific. During this past year we have developed a new calorimetric method that is generally applicable for measuring the critical temperature for membrane assembly, and for specific chemical contributions to stability of membrane bilayers.